1. Field of the Disclosure
The disclosure relates generally to methods for preventing and/or extinguishing fires and, more specifically, to methods for applying water-laden polymer particles to a surface to prevent and/or extinguish fires.
2. Brief Description of Related Technology
Water is commonly used to extinguish fires and to prevent the spread thereof to nearby structures. Water has several beneficial effects when applied to a fire, including heat removal and oxygen deprivation. When water is directed at a structure adjacent a fire to prevent its spread thereto, the fire must provide enough heat to evaporate the water on (or in the materials of) the adjacent structure before the adjacent structure can reach its combustion or ignition temperature.
One disadvantage to using water to prevent a fire from spreading to a nearby structure is that most of the water directed at the structure does not soak into the structure to provide fire protection, but rather tends to run off the structure to the ground. Consequently, a significant quantity of water is wasted. Another disadvantage is that any water that does soak into the structure provides only limited protection against the fire because most structures only absorb a limited amount of water, and that limited amount of absorbed water quickly evaporates. Therefore, significant manpower must be expended to continuously reapply water on nearby structures to provide them with continuing fire protection.
A disadvantage to using water to extinguish fires is that a considerable amount of the water does not directly fight or extinguish the fire because of the run-off problem described above. Another disadvantage to using water in extinguishing fires is that the water sprayed directly on the fire evaporates at an upper level of the fire, with the result that significantly less water than is applied is able to penetrate sufficiently to extinguish the base of the fire.
To address the above disadvantages of using water (by itself) to fight fires, U.S. Pat. No. 5,190,110 to von Blücher et al. describes using an aqueous system comprising dry absorbent polymers to extinguish and/or prevent fires. The polymer particles have particle sizes from 20 microns to 500 microns, and are dispersed in water by stirring or pumping, such that the resultant viscosity does not exceed 100 centipoises (cps). This system contains discrete polymer particles that absorb water, without being soluble in water. Thus, the particles are entrained in the water, permitting their application directly to a fire. The dry, solid granular particles are typically pre-mixed with the water source. Alternatively, the dry, solid granular particles can also be added directly in advance of the nozzle. This alternative method does not provide sufficient time for the particles to swell and, consequently, the viscosity is not increased sufficiently to allow the particles to adhere to surfaces.
U.S. Pat. No. 4,978,460 to von Blücher et al. also describes using an aqueous system comprising dry absorbent polymers to extinguish and/or prevent fires. The dry, solid polymer particles of the '460 patent are encased by a water-soluble release agent to prevent agglutination of the particles. The time that it takes for the encapsulated solid granular particles to swell (i.e., expand from the absorption of water) ranges from ten seconds to several minutes. When fighting a fire with typical hose lengths, ten seconds is longer than practical for the water to be retained in a fire hose. Thus, when such encased polymer particles are used with standard fire-fighting equipment, there is not sufficient time for the particles to swell, and the viscosity is not increased sufficiently to allow the particles to adhere to surfaces.
U.S. Pat. No. 3,758,641 to Zweigle also describes using dry, solid, granular polymer particles with high water absorption in firefighting applications. Use of the disclosed particles is best accomplished with special, additional firefighting equipment.
Due to the dry, solid, granular nature of the aforementioned state-of-the-art firefighting, water-absorbent polymeric particles, it is difficult, if not impossible, to use such polymers in many firefighting applications. For example, eduction of such polymers into a standard firefighting hose with standard equipment is nearly impossible because of the particulate nature of such polymers. Moreover, the dry, solid nature of the polymers promotes agglutination of the particles and subsequent blockage of water flow from the firefighting hose. It is therefore sometimes necessary to provide special equipment such as “pumps and spray nozzles adapted for handling for such materials” to use the dry, solid granular particles in firefighting applications (see, for example, the '641 patent to Zweigle).
Additionally, if a natural source of water, such as a creek or a river, is to be used as the water source, it is impossible to pre-mix the polymer by batch adding it to the water source. For example, if one poured the polymer additive into a stream or river, most of the polymer additive will simply flow past the point of suction of the water for use in combating fires.